The present invention relates to a data communication device, and more specifically to an error processing technique used in a data communication device such as a facsimile device.
Conventionally in a data communication device such as a facsimile device, various device noise is generated internally during operation of the device itself. For example, actuation noise of an electric motor is produced when the motor is feeding a sheet to be scanned or printed.
Before transmitting image data, a TCF signal (transmission confirmation signal) is transmitted between a calling facsimile device (hereinafter referred to as a calling station) and a called facsimile device (hereinafter referred to as a called station). During TCF transmission, a transmission baud rate is established between the calling and called stations. This transmission baud rate is determined based on the electrical noise present in the communication channel between the two stations.
However, in the conventional facsimile devices, the electrical noise present in the communication channel during TCF transmission is different than the electrical noise present during image transmission, since the motors used to feed the scanned sheet and printed sheet are not actuated during TCF transmission. Therefore, a baud rate established during TCF transmission may be inadequate for proper transmission of the image data, resulting in many data errors during transmission of the image data.
One solution proposed to overcome this defect is to actuate the driving motors of the called station during transmission of the TCF signal in order to more accurately determine a baud rate during the transmission of image data.
However, for facsimile devices that employ a memory for storing a document, i.e., data to be transmitted or received data, it is unnecessary to have the motors driven during image data transmission/reception. If the motor is actuated during the transmission/reception of the TCF signal, more electrical noise is present on the communication line than will be present during the transmission of image data. Thus, a baud rate that is determined for use during image data transmission/reception will be lower than is necessary for proper data transfer. This results in a longer transmission time being required to transfer the image data than is necessary.